Pear — Food safety facts
Feed with care · Cats · full breakdown on the linked food page
Flesh is safe. Remove the core and seeds — seeds contain cyanide compounds.
Short answer
Yes, a small slice of pear flesh is safe for your cat to try, but you must remove the core and all seeds first. The seeds contain cyanide compounds which are toxic, and the hard core is a choking hazard. Only offer a tiny amount of the soft flesh as an infrequent treat, and monitor for any stomach upset afterwards.